Layered fleet air defence depended on fighters and engines

Exercises could produce false confidence because pilots naturally attacked prestigious capital ships rather than the destroyers whose anti-aircraft arcs also mattered. The Navy's layered doctrine expected fighters to disrupt formations, heavy guns to break them into smaller groups, and weapons such as the two-pounder pom-pom to engage individual attackers. Existing 4.7-inch destroyer guns could contribute to task-group defence but lacked the elevation needed for close self-defence, while a 4.5-inch dual-purpose solution was still developing. Fighter Command and the Fleet Air Arm competed for scarce high-performance Merlin engines, and the Air Ministry also prioritised heavy bombers. Aircraft procurement was therefore an industrial allocation problem as well as a doctrinal one.